Conventionally, for wireless communication machines, such as mobile phones, or information processing machines, such as PCs (personal computers) and servers, a regulator for power conversion is used that converts an input power into a desired output power.
Wireless communication machines and information processing machines in recent years tend to have an increasing peak of a load current as they become enhanced in performances and functions, while there is a demand for stable supply of power over a long period of time by reducing power consumption. Therefore, it is important to use a regulator with high power conversion efficiency.
In the meanwhile, there are various types of regulators depending on the differences in, for example, the rated current or the rated voltage, and the characteristics of the power conversion efficiency relative to the output current value differ with the type of a regulator.
For example, even in a case of items in an identical series having an equivalent internal circuit only different in a rated current value, the regulators sometimes differ in the characteristics of the power conversion efficiency. In this case, when selecting a high power regulator in conformity with the peak load current, the power conversion efficiency of the high power regulator sometimes become worse under low load compared with the power conversion efficiency of a low power regulator.
With that, there is a regulator device that is equipped with a plurality of regulators with different power conversion efficiency and selectively switches to a regulator with optimum power conversion efficiency in accordance with the output current value.
The following is reference document:    [Document 1] Japanese Laid-open Patent Publication No. 11-353040